Thursday, September 07, 2006

Visual Processing and the Immortality of the Soul

Life after death is a very implausible idea, yet many people, in many different cultures, believe in it. For those of us who do not share that belief and are puzzled by all the reasonable and intelligent people who do, the obvious explanation is wishful thinking. But many of the same people also believe in some version of Hell—and, however useful that may be for threatening misbehaving children, it is not what wishful thinking would suggest as a possible future fate for oneself. I have an entirely different explanation to offer. I propose that the belief in the immortality of the soul is a consequence of the way in which our visual system processes information.

Looking around me, what I see is a collection of recognizable objects—a computer screen, a plastic cup half full of diet coke, a telephone and, in my very messy office, a lot of other things. But none of that is in the information feeding from my retinas to my optic nerves. That information consists of a visual field--a flat plane of various colored regions (actually two, one for each eye). Somehow the software in my brain is converting that very uninformative body of data into a reasonably accurate model of the bit of the world I am looking at.

As with many other things the brain does, it only became clear how hard it was when people started trying to write software to duplicate it and discovered that they couldn't—the information coming in was not adequate to generate the information going out. The explanation they came up with was that the brain cheats. In addition to using the information coming in through the retina, it also uses a body of information, generated by some combination of evolution and experience, about what the world is like, information that lets it discard most of the possible explanations of what it gets from the retina in favor of a small number of likely ones.

One such piece of information is persistance of objects. Having recognized the oddly shaped green region to the right of my visual field as the top half of a plastic cup (the bottom half is dark because of the diet coke showing through), my software does not have to redo the analysis three seconds later—even though the region is no longer in the same part of the visual field, my head having turned a little in the meanwhile. Part of the hardwired information is that if the cup was there recently, it is probably still there, or close. Being a rigid object, it is probably still about the same shape, even if a change in the angle at which I am observing it makes it look different.

Some things violate the rules—soap bubbles, for example. That is one of the reasons why soap bubbles seem like odd, almost magical, objects. And there are optical illusions that take advantage of the rules to trick us into seeing what isn't there. But, on the whole, our image processing rules and the software containing them work very well, much better than any software we can ourselves write.

Things persist. People are things, but things of a special sort; when you talk with a friend over the phone it is not his body you are aware of but the person inside. When he dies the body is still there but the person is not—which is intuitively impossible, since the knowledge of the persistence of things is hardwired into your brain.

36 Comments:

Pascal Boyer's book, _Religion Explained_, argues that the core aspects of religious belief are explained by various inferential schemas that we have, applied in contexts where they don't work. This recent BBC article about demonstrations by Bruce Hood makes a similar point.

Interesting point of view. I personally suspect that the brain hardware in question doesn't have as much to do with the visual system, as with our "intuitive psychology" system. Normal humans have a model of other humans' minds that allows us to reason about their motivations, emotions, and ultimately their likely future behavior. Persistence is a property of of our intuitive model of others' minds; i.e., just because Joe isn't physically present doesn't mean he isn't planning to steal my food, abscond with my mate, throw me a birthday party, or start a fight with my enemy.

Joe's death provides this mental system with a difficult boundary condition; Joe is no longer physically present, but our minds keep around a model of his mind. So his mental processes continue to seem very real; grieving people often express this with words to the effect that "It feels like Joe's going to come back any minute." Religious ideas that exploit this boundary condition are intuitively appealing.

Here is an interesting article about the origins of religion: Is God an Accident? by by Paul Bloom. "[...] the universal themes of religion are not learned. They emerge as accidental by-products of our mental systems. They are part of human nature."

Actually, you're not entirely right in your model of visual processing. In particular, the brain does not remember that an object that was there a moment ago is still there in most cases.

You can test this with simple equipment -- the classic experiment shows a picture to a person, blanks the screen for a few tens of milliseconds so the brain's motion detection circuits aren't going to be triggered, and then shows a second picture to the subject with an important detail changed. It is extraordinary how hard it is to notice what has changed. I've had this performed on me, and I was stunned to see that major portions of an image could be removed without my being able to say if there even was a change.

The phenomenon is bad enough that you can do the following really evil experiment: you can show a man a picture of two women, ask him to point at the one he considers more beautiful, and while his arm is moving and clearly about to point at one side, do the blank and change trick, exchanging the two women. Almost all subjects continue to move their arm in the direction it was going before, and almost all of them produce rationalizations for why they pointed at the one woman versus the other even though they intended to point elsewhere at the moment they started to move their arm.

The literature on "change blindness" and related phenomena is fascinating -- I suggest reading up on it. It makes you doubt all your internal assumptions about consciousness.

Interesting argument, I'd just like to note two things.1) People are wrong about most things at a given time...2) Just because Christians believe in a Hell does not disprove the notion of wishful thinking as best explanation for belief in the aferlife. No Christians actually believe that THEY are the ones who are going to end up there. No, Hell is reserved for us heathens. (Sort of like how statists believe laws are for everybody else.)Alcibiades

The BBC item about Hood's finding that people 'humanise' inanimate objects is interesting.

But it doesn't explain why people 'humanise' humans. Why not treat them as objects too? Presumably a society where people treated other people, or at least strangers, as mere objects wouldn't be that different from a nation of sociopaths or psychopaths.

I suspect a nation of sociopaths wouldn't survive very long. Somehow we need to internalise a set of social rules just as we internalise a Chomskyian grammar. We need humans who act as if 'natural laws' really do exist.

A nation that internalised natural rights would outperform and outsurvive a nation of sociopaths. So maybe there is some group selection at work. Maybe this accounts for the apparent or near universality, at least the great commonality, of moral law principles that C S Lewis summarised in his appendix to his book, "The Abolition Of Man".

If we fool ourselves into treating other humans humanely, that others have some worthwhile human-ness, it is understandable that this quality is seen to persist over and above death. Evolved traits rarely have a 'perfect fit'. Evolution is ordinal not cardinal. It 'satisfices'. In evolved systems, as Stephen J Gould tells us, perfect adaptations are rare, if they ever exist. Adaptations merely need to be better than the competition.

Building a brain susceptible to the delusion of treating other humans humanely only needs to be good enough to achieve selective domination (evolutionary stable strategy - i.e. ESS) over sociopathic brain designs.

Most people don't have trouble believing that a building, or a car, or a supply of food can cease to be, or has ceased to be. Germans have trouble even remembering where the Berlin Wall used to be. The wishful thinking explanation still sounds more plausible than the neurological one.

Good example of the persistence of vision assumption in action is a clip movie mess-ups:http://youtube.com/watch?v=lpp0sONigrwWe don't really notice errors like things dissappearing between cut scenes until they are pointed out, as they are here...Alcibiades

alcibiades/anonymous wrote:"No Christians actually believe that THEY are the ones who are going to end up there. No, Hell is reserved for us heathens."

While it is rare, there are a few, but they don't last long. They either commit suicide, convert to atheism, resign themselves and stop calling themselves Christian, or redouble their efforts at meeting whatever requirement they think they lack, or convert to another religion. Or, they resolve the issue by assuming that hell is for other people, just as you said. I know a redoubler, an atheist, and a suicide. I don't know a resolver, but they presumably wouldn't describe themselves as such. How do you know you have met a resolver?

I agree with K.A. on the visual processing thing. More often we thow out or simplify vis. imput than manufacture it.

But on life after death?

"Cattle die and kinsmen dieand so one dies onselfone thing I know never diesthe honour of a man's name"

A human really is more than a piece of animated flesh. A person can (and usually does) remain a real experience to others after they die. Who did write Havamal? I have learned from that person, my experience of them is real and tangible. Similarly people who have died and whom I've known, or who my friends have known (in one case this is quite extreme)

Why not extrapolate that, as we can continue to experience a person after death, they can continue to experience? I think to 'know' that there is an afterlife is irrational. But so is to 'know' that there is none.

Some Christian sects teach that it is wrong to have an opinion about your soul's destination. To believe you are going to heaven is the sin of pride; to believe you are going to hell is the sin of despair.

Is it too obvious to observe that wishful thinking accounts for believing in hell for people you don't like?

For myself, I think the strongest reason for an intuitive suspicion of an afterlife, is the apparent absurdity of the world continuing without me to perceive it.

"I think to 'know' that there is an afterlife is irrational. But so is to 'know' that there is none." A summation of the question in 2 sentences! Nice Work! Nothing is more amusing than the "finite" mocking the existence of infinite with the assumptions of a finite understanding....good work....

It's an interesting piece, but I think consistent with the explanation I offered.

Perry offers evidence against my explanation which seems to me to be evidence for it. If your built-in assumption is that the object that was there a moment ago is still there, then it isn't surprising that you see it as still the same, even when it isn't.

Alcibiades thinks Christians believe Hell is only for unbelievers. I believe that's clearly false. In the view of most Christians in history, Hell was also for sinful Christians, with details of how you got in or out varying with the sect. And there appear to have been lots of Christians who worried that they might end up in.

I'd like to clarify, since David doesn't seem to understand the import of the research.

Our common belief is that we look at a scene, parse it, and build an internal model of what we are viewing which persists even when we are not looking at the scene. Your posting implicitly assumes this view of visual cognition.

The best research now seems to demonstrate that we do not, in fact, build any such model of the outside world in detail. It is a nice and simple model of how one might naively assume visual processing works, but it is, in fact, completely incorrect so far as our best experiments can tell.

Instead of producing a detailed model of a scene, our brains evolved to simply re-parse the sections of the scene we needed to learn about on an "on demand" basis. We generally speaking are capable of paying actual attention to only a small number of objects within the scene -- we have some detailed research on how many under what circumstances but that's not important right here -- and for the rest of the scene, we maintain at best a sort of "sketch".

The reason we do not notice that major portions of a scene have been removed or replaced in contradiction to our internal model is because there is no model to contradict. You never actually were storing information about the vase of flowers on the table in the picture, so the sudden absense of the vase, provided it is removed from the scene in a way that does not trigger your motion detection apparatus, does not trigger any sort of mental response.

What is more interesting is why dogmatic belief in reductionistic materialism persists, despite the massive evidence that that model does not account for the scientific and anectdotal data. Just like fundamentalist Christians who cannot accept evidence for common descent, committed reductionists always come up with excuses why the evidence is flawed, why all the eyewitness accounts are mistaken, and why their theory of the universe should trump the observations.

The reason for this is simple - people are loathe to give up their deeply-cherished belief systems, whatever they may be. For example, how many readers of this blog are willing to even consider the possibility that consciousness is not simply a function of brain states? Mind = brain is an unchallengable axiom to many people's world-view, and they are incapable of putting down that belief to examine alternative explanations of the facts.

"In the view of most Christians in history, Hell was also for sinful Christians, with details of how you got in or out varying with the sect."

I don't see the problem here. I am part of Sect X, I believe that if I act in some specific manner that I am heading for the Pearlies; I further believe that Other People, in other sects, are not abiding by these rules and are going to Hell. In turn, they earnestly believe they are going to Heaven, and I to Hell. Different admission criteria among sects, and yet all believe that they themselves (and their friends and family) are going to Heaven, and everyone else, to Hell.

I have yet to see a preacher speculate on the deceased's ultimate destination. I have yet to see a Chistian actually behave in the manner of someone who believed that sinfulness during this, a tiny sliver of their eternal existence, could earn them eternal torment.

So, I think belief in a hell (for people who aren't me) accords just fine with a wishful-thinking-explanation of belief in the afterlife.

The persistence of vision... well, maybe. I still think wishful thinking is probably the most important explanation of the afterlife. "Surely there can't be less than a century of me..."

As for heaven and hell, bear in mind that Christianity dates from ancient times. Until the modern era, most people could easily see a few rich people living in luxury (heaven) and more than a few people suffering horribly (hell) -- from punishment, disease, etc.

The afterlife, as they saw it, would be more of the same, except they wistfully hoped that people would be allocated to luxury or torture according to virtue rather than according to luck, skill, knowing the right people, and keeping on the right side of them.

By the way, I'm pleased to see you're not religious. For us here in Europe, the religiosity of the USA in general is very hard to understand.

I still think wishful thinking is probably the most important explanation of the afterlife.

Or maybe the fact that people have experienced it and come back to make reports. . . Even reductionistic atheists who were previously convinced it was all a bunch of crap.

By the way, I'm pleased to see you're not religious. For us here in Europe, the religiosity of the USA in general is very hard to understand.

There are two faith-based opinions on the "afterlife". One is people to who cling to a traditional religious teaching of heaven and hell, nirvana, etc. The other is the faith-based opinion of reductionists who cling to a particular set of scientific models without questioning them.

I am an atheist and, for me, believing even in Hell would be wishful thinking!

Something, even if it involves pain, whips and hot sulfur for an eternity is better than nothing, than the void of death.

Anyway I think life itself is an illusion, there is no continuity of consciousness, on every instant we vanish, die, disappear and a new self with a memory of previous events is born and believes from this memory in the continuity of his consciousness. It is only our memory that gives us the illusion of existence.

Anyway I think life itself is an illusion, there is no continuity of consciousness, on every instant we vanish, die, disappear and a new self with a memory of previous events is born and believes from this memory in the continuity of his consciousness. It is only our memory that gives us the illusion of existence.

You're close to the truth.

In fact, there is no individual personal identity. Consciousness is experiencing itself right now through the set of experiences known as "AB" and is also experiencing itself through the set of experiences known as "MC" and "David Friedman" and every other locus of awareness.

As Albert Einstein put it, personal selfhood is "an optical delusion of consciousness". The personal self is much like one of the characters in a dream - seemingly separate, but upon awakening it was seen that all of the characters were in fact a part of the dreamer.

In the same way, personal identity is a dream playing itself out upon the screen of awareness. The dream of selfhood can be awakened from while still in the body in the same way that one can lucidly dream. Or the dream can continue after death of the body, into dreams of personal selfhood experiencing "heaven", "hell" or other such realms. But eventually the dream is seen through and a recognition of what is really going on occurs.

So your skepticism of the individual personal sense of self is quite valid, and on the right track.

I completely agree with you. My vision of life could be described as both everettist and solipsist. Every other self is a creation of my experience of the world which is influenced by my own consciousness. I don't believe I am the only being but rather that by perceiving the world I place every other consciousness in a state from which they themselves drift by the process of their own consciousness. Some sort of entwining.Would that describe your vision as well?

Let's put aside Christianity, and think about what immortality of the soul means. This is tough, because we need to think what "soul" and "person" mean. The original post said

"...when you talk with a friend over the phone it is not his body you are aware of but the person inside. When he dies the body is still there but the person is not..."

Actually, the reverse is true. If when my friend talks, it is the person I are aware of, then if he dies after, say, leaving a message on my answering machine, his body may be taken away, but he is just as alive--to me-- as he was before.

It is quite conceivable that technology will advance so that we can write software that replicates a given person perfectly--that is, so well that an observer can't detect any flaws. If the "real" person dies, does he then cease to exist?

Simple folk realize this puzzle, on a simple level. Someone dies, but his mark on the world persists. So is he really gone, or not?

eric,So, from the perspective of the person receiving the phone message, in a sense, yes, the dead individual who left him a message is still alive.BUTThe message-giver is dead.He is no longer conscious.He no longer sees, hears, feels, acts.DeadPerson's phone messages, his blog posts, the memories of him in the minds of others -- these all still exist -- but he, in terms of a conscious entity, most certainly does not.Alcibiades

I completely agree with you. My vision of life could be described as both everettist and solipsist. Every other self is a creation of my experience of the world which is influenced by my own consciousness. I don't believe I am the only being but rather that by perceiving the world I place every other consciousness in a state from which they themselves drift by the process of their own consciousness. Some sort of entwining.Would that describe your vision as well?

AB,

I'm not quite sure what you are saying exactly. Can you elaborate a bit?

I can’t help thinking of this issue from a more biological or Darwinian point of view. Survival instincts in humans, just as in all other animals, are extremely strong. In fact, they are the backbone of our nature—or otherwise we, as specie, would not have survived as long as we have. But unlike animals, we know how to think, or, what’s more important in this case, how to imagine. This combination of the extreme urge (instinct) to survive and the ability to think creatively, or imagine, results in our acceptance of something which we may even find illogical, such as life after death. In other words we just can’t get over of our natural (genetic) urge to live. But then that would mean that those of us who don’t believe in life after death are able to overcome this urge. Does it mean that their survival instincts are weaker?

It's really hard (or perhaps impossible) to imagine oneself not existing. No matter how materialistic I am, if I try to conceive my own mortality, I can only do it in an abstract vague way. So, the concept of personal immortality might be not a feature, but a limitation of our brains. It's not hard to see why evolution didn't bother to install it.